Magnetron beam tube noise generators



Jan. 29, 1963 P. E. LA BEAUME MAGNETRON BEAM TUBE NOISE GENERATORS 2Sheets-Sheet 1 Filed July 18, 1960 INVENTOR.

PAUL LBIBEAUME BY Mafia ATTORNEY Jan. 29, 1963 P. E. LA BEAUME 8MAGNETRON BEAM TUBE NOISE GENERATORS Filed July 18, 1960 2 Sheets-Sheet2 3O OUTPUT I8 i lLH M on 5" l6 33 PULSE SOURCE F g. 3

A OUTPUT \V \V on 5" F L up F LO P k 4 45 4e 44-i 42 NPUT I INVENTOR.

PAUL La BEA um:

A TTORNE Y 3,@?h,ll8 Patented Jan. 2%, 1963 3,676,113 MAGNETRQN BEAMTUBE Niftl-SE GENERATQRS iaui E. La Eeaume, Livingston, NJ, assignor toBurroughs Qcrporation, Detroit, Mich, a corporation at Michigan FiledJuly 18, 196i), Ser. No. 43,438 d Claims. (til. 315-36) This inventionrelates to magnetron-type electron discharge tubes and to improvementsin the construction and operation of such tubes, particularly asnoise-generators.

One form 01' magnetron tube, to which the principles of the inventionapply, comprisese a multi-position device and includes an electrodeassembly which includes an elongated central cathode and a plurality ofgroups of elongated electrodes surrounding the cathode and se curedtogether at their opposite ends by means of insulating end disks orplates. All of the electrodes are oriented substantially parallel toeach other. An external cylindrical magnet surrounds the tube envelopeand elecrode assembly.

in operation of this type of tube, a beam of current flows from thecentral cathode and is urged to rotate around the tube under theinfluence of crossed electric and magnetic fields. The beam may remainstatic at one group of electrodes, or it may be switched from positionto position by the application of proper potentials to selected ones ofthe tube electrodes.

If the beam is static, an output current is obtained, the magnitude ofwhich is determined by the various operating parameters. However, forany one set of operating conditions, optimum utilization of the electronbeam and maximum output current, particularly noise output, are notachieved.

The principles and objects of the present invention are concerned withthe provision of an improved arrangement for a multi-position magnetronbeam tube and an improved circuit for operating the same wherebyfavorably high output current and high noise output are obtained.

In brief, a multi-position magnetron tube embodying the inventioncomprises, in a suitable envelope, an electrode assembly including acentral longitudinally elongated cathode electrode surrounded by groupsof longitudinally elongated electrodes which are adapted to form andreceive an electron beam from the cathode. Each group of electrodesincludes an output or target electrode from which an output signal maybe derived and a spade electrode which may be used to form and hold anelectron beam on its associated target electrode. A cylindricalpermanent magnet surrounds the tube and provides the requiredlongitudinal magnetic field. In operation of the tube, an electron beamis not switched from position to position, but is maintained in a staticcondition, flowing simultaneously to two opposed target electrodes whichare coupled together and from which the desired output signal isderived. This arrangement provides more efficient utilization of theelectron beam and increased noise signal output.

The invention is described in greater detail by reference to thedrawing, wherein:

FIG. 1 is a sectional view of a multi-position magnetron tube used inpracticing the invention;

PEG. 2 is a schematic representation of the tube of PEG. 1 and a circuitembodying the invention;

FIG. 3 is a schematic representation of a modification of the circuit ofthe invention; and

FIG. 4 is a schematic representation of another modification of thecircuit of the invention.

The principles of the invention are applicable to magnetron tubes and,particularly, to a multi-position type 6700 magnetron beam switchingtube which is shown as tube it in FIGS. 1 and 2. This type of tube iscylindrical in form and includes an envelope 12 which contains a centrallongitudinally elongated cathode 14 and ten groups of electrodes spacedradially equidistantly from the cathode and surrounding the cathode.Each group of electrodes includes a generally U-shaped elongated spadeelectrode 16 and a generally L.-shaped target electrode 18 positioned sothat each target occupies the space between adjacent spade electrodes.Each spade electrode serves to form and hold an electron beam on itscorresponding target electrode. A type 6709 tube generally includesrod-like switching electrodes; however, since these electrodes are notused in practicing the invention, they are not shown in the drawing. Thetube 10 also includes a cylindrical hollow magnet 22. surrounding theenvelope and providing an axial magnetic field which is utilized inconjunction with electric fields within the tube to control electronbeam flow.

In the circuit of the invention shown in FIG. 2, the tube 10 is shownschematically with its electrodes arrayed in linear form. The electrodeand circuit arrangement are such that a double electron beam is formedand electrons flow from the cathode to two opposed groups of electrodesincluding the targets 18' which are assumed to be at the O and 5positions or groups of electrodes in tube it In the circuit, the spadeelectrodes 36 associated with targets 18' are elcc trically connected bya suitable lead 24. Similarly, the targets 18 at the same positions areconnected together by a lead 26 which is coupled through a load resistor28 both to ground and to a source of positive DC. potential. An outputterminal 3%} is also connected to the two targets 1-8. All of the otherelectrodes are electrically connected together in any suitable fashionby leads 32, 3d, and 36 so that, electrically, they comprise a singleunit.

The relative potentials employed with the tube 10 to obtain two electronbeams are as follows. The cathode is coupled to a DC. potential V whichis negative with respect to ground; the opposed 0 and 5 spades arecoupled to a DC. potential V which is positive with respect to thecathode; and all other electrodes are coupled to a DC. potential V whichis made highly positive with respect to the cathode. In one operatingcircuit, V was about volts positive, V was about '75 volts negative, Vwas about volts negative, and V was about 280 volts positive.

In operation of the circuit of FIG. 2, electrons emitted by the cathode14 are divided into two beams with one beam flowing to each of thetargets 13. This current flow is ettccted by the electrode connectionsand by the relative potentials, particularly the negative potentials inthe spade electrodes 16'.

Alternative arrangements for operating the tube iii are shown in FIGS. 3and 4. Since only the 0 and 5 electrode connections are modified, onlythese are shown and the others are omitted. According to thesealternatives, the spade electrodes at the G and 5" positions have pulsesapplied to them, rather than the constant D.C. source shown in FIG. 2.In FIG. 3, a source 33 of negative pulses of about 100 volts inamplitude has its output 4t} coupled to both spade electrodes 16' sothat both spade electrodes are pulsed negative at the same time andnoise output is obtained during this period. In FIG. 4, a flip-floppulse source 42 is provided having a single input 44 and two outputs 46and 48, one of which is connected to the 0 spade, the other of which isconnected to the 5 spade. With this arrangement, the 0 and 5 spades arealternatively pulsed negative and noise output is obtained alternatelyfrom the target electrodes 18'.

The present invention thus provides a novel circuit arrangement foroperating a magnetron beam switching tube. To the extent that this typeof operation can be compared with current flow to a single outputelectrode, under similar operating conditions, the present inventionprovides greater noise output over a wider frequency range.

What is claimed is:

1. A double beam noise-generating circuit including a magnetron beamswitching tube of the type utilizing crossed electric and magneticfields, said tube having a cathode and a plurality of groups ofelectrodes surrounding said cathode; each group including a tar-getelectrode which receives an electron beam and produces an output signaltherefrom; and a spade electrode which holds an electron beam on itsassociated target electrode; means providing a longitudinal magneticfield in said tube; a pair of oppositely disposed spade electrodes beingconnected together and to a source of negative potential, the targetelectrodes associated with said spade electrodes being coupled togetherto an output terminal and to a source of positive D.C. potential, saidcathode being coupled to a negative D.C. potential, all of the otherelectrodes being connected together and to a source of positive D.C.potential, the aforesaid electrode connections causing electrons emittedby said cathode to form two beams which flow one to each of the pair ofoppositely disposed target electrodes associated with said pair ofoppositely disposed spade electrodes whereby high noise current outputis obtained.

2. The circuit defined in claim 1 wherein the potential applied to saidoppositely disposed spade electrodes is more negative than the potentialapplied to said cathode.

3. The circuit defined in claim 1 wherein the negative potential coupledto said oppositely disposed spade electrodes is a D.C. potential.

4. The circuit defined in claim 1 wherein the source of negativepotential coupled to said oppositely disposed spade electrodes is asource of negative pulses.

5. The circuit defined in claim 1 wherein the'source of negativepotential coupled to said oppositely disposed spade electrodes is aflip-flop having a single input and two outputs coupled one to each ofsaid spade electrodes.

1. A DOUBLE BEAM NOISE-GENERATING CIRCUIT INCLUDING A MAGNETRON BEAMSWITCHING TUBE OF THE TYPE UTILIZING CROSSED ELECTRIC AND MAGNETICFIELDS, SAID TUBE HAVING A CATHODE AND A PLURALITY OF GROUPS OFELECTRODES SURROUNDING SAID CATHODE; EACH GROUP INCLUDING A TARGETELECTRODE WHICH RECEIVES AN ELECTRON BEAM AND PRODUCES AN OUTPUT SIGNALTHEREFROM, AND A SPADE ELECTRODE WHICH HOLDS AN ELECTRON BEAM ON ITSASSOCIATED TARGET ELECTRODE; MEANS PROVIDING A LONGITUDINAL MAGNETICFIELD IN SAID TUBE; A PAIR OF OPPOSITELY DISPOSED SPADE ELECTRODES BEINGCONNECTED TOGETHER AND TO A SOURCE OF NEGATIVE POTENTIAL, THE TARGETELECTRODES ASSOCIATED WITH SAID SPADE ELECTRODES BEING COUPLED TOGETHERTO AN OUTPUT TERMINAL AND TO A SOURCE OF POSITIVE D.C. POTENTIAL, SAIDCATHODE BEING COUPLED TO A NEGATIVE D.C. POTENTIAL, ALL OF THE OTHERELECTRODES BEING CONNECTED TOGETHER AND TO A SOURCE OF POSITIVE D.C.POTENTIAL, THE AFORESAID ELECTRODE CONNECTIONS CAUSING ELECTRONS EMITTEDBY SAID CATHODE TO FORM TWO BEAMS WHICH FLOW ONE TO EACH OF THE PAIR OFOPPOSITELY DISPOSED TARGET ELECTRODES ASSOCIATED WITH SAID PAIR OFOPPOSITELY DISPOSED SPADE ELECTRODES WHEREBY HIGH NOISE CURRENT OUTPUTIS OBTAINED.